// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <string.h>

#include <algorithm>

#include "base/logging.h"
#include "net/der/input.h"

namespace net {

namespace der {

    Input::Input()
        : data_(nullptr)
        , len_(0)
    {
    }

    Input::Input(const uint8_t* data, size_t len)
        : data_(data)
        , len_(len)
    {
    }

    Input::Input(const base::StringPiece& in)
        : data_(reinterpret_cast<const uint8_t*>(in.data()))
        , len_(in.length())
    {
    }

    Input::Input(const std::string* s)
        : Input(base::StringPiece(*s))
    {
    }

    std::string Input::AsString() const
    {
        return std::string(reinterpret_cast<const char*>(data_), len_);
    }

    base::StringPiece Input::AsStringPiece() const
    {
        return base::StringPiece(reinterpret_cast<const char*>(data_), len_);
    }

    bool operator==(const Input& lhs, const Input& rhs)
    {
        if (lhs.Length() != rhs.Length())
            return false;
        return memcmp(lhs.UnsafeData(), rhs.UnsafeData(), lhs.Length()) == 0;
    }

    bool operator!=(const Input& lhs, const Input& rhs)
    {
        return !(lhs == rhs);
    }

    bool operator<(const Input& lhs, const Input& rhs)
    {
        return std::lexicographical_compare(
            lhs.UnsafeData(), lhs.UnsafeData() + lhs.Length(), rhs.UnsafeData(),
            rhs.UnsafeData() + rhs.Length());
    }

    ByteReader::ByteReader(const Input& in)
        : data_(in.UnsafeData())
        , len_(in.Length())
    {
    }

    bool ByteReader::ReadByte(uint8_t* byte_p)
    {
        if (!HasMore())
            return false;
        *byte_p = *data_;
        Advance(1);
        return true;
    }

    bool ByteReader::ReadBytes(size_t len, Input* out)
    {
        if (len > len_)
            return false;
        *out = Input(data_, len);
        Advance(len);
        return true;
    }

    // Returns whether there is any more data to be read.
    bool ByteReader::HasMore()
    {
        return len_ > 0;
    }

    void ByteReader::Advance(size_t len)
    {
        CHECK_LE(len, len_);
        data_ += len;
        len_ -= len;
    }

} // namespace der

} // namespace net
